src/display/inkscape-cairo.cpp

   1 /*
   2  * Helper functions to use cairo with inkscape
   3  *
   4  * Copyright (C) 2007 bulia byak
   5  *
   6  * Released under GNU GPL
   7  *
   8  */
   9
  10 #include <cairo.h>
  11
  12 #ifdef HAVE_CONFIG_H
  13 # include <config.h>
  14 #endif
  15 #include <libnr/n-art-bpath.h>
  16 #include <libnr/nr-matrix-ops.h>
  17 #include <libnr/nr-matrix-fns.h>
  18 #include <libnr/nr-pixblock.h>
  19 #include "../style.h"
  20 #include "nr-arena.h"
  21
  22
  23 /** Creates a cairo context to render to the given pixblock on the given area */
  24 cairo_t *
  25 nr_create_cairo_context (NRRectL *area, NRPixBlock *pb)
  26 {
  27     if (!nr_rect_l_test_intersect (&pb->area, area))
  28         return NULL;
  29
  30     NRRectL clip;
  31     nr_rect_l_intersect (&clip, &pb->area, area);
  32     unsigned char *dpx = NR_PIXBLOCK_PX (pb) + (clip.y0 - pb->area.y0) * pb->rs + NR_PIXBLOCK_BPP (pb) * (clip.x0 - pb->area.x0);
  33     int width = area->x1 - area->x0;
  34     int height = area->y1 - area->y0;
  35     // even though cairo cannot draw in nonpremul mode, select ARGB32 for R8G8B8A8N as the closest; later eliminate R8G8B8A8N everywhere
  36     cairo_surface_t* cst = cairo_image_surface_create_for_data
  37         (dpx,
  38          ((pb->mode == NR_PIXBLOCK_MODE_R8G8B8A8P || pb->mode == NR_PIXBLOCK_MODE_R8G8B8A8N) ? CAIRO_FORMAT_ARGB32 : (pb->mode == NR_PIXBLOCK_MODE_R8G8B8? CAIRO_FORMAT_RGB24 : CAIRO_FORMAT_A8)),
  39          width,
  40          height,
  41          pb->rs);
  42     cairo_t *ct = cairo_create (cst);
  43
  44     return ct;
  45 }
  46
  47 /** Feeds path-creating calls to the cairo context translating them from the SPCurve, with the given transform and shift */
  48 void
  49 feed_curve_to_cairo (cairo_t *ct, NArtBpath *bpath, NR::Matrix trans, NR::Point shift)
  50 {
  51     NR::Point lastX(0,0);
  52     bool  closed = false;
  53     for (int i = 0; bpath[i].code != NR_END; i++) {
  54         switch (bpath[i].code) {
  55             case NR_MOVETO_OPEN:
  56             case NR_MOVETO:
  57                 if (closed) cairo_close_path(ct);
  58                 closed = (bpath[i].code == NR_MOVETO);
  59                 lastX[NR::X] = bpath[i].x3;
  60                 lastX[NR::Y] = bpath[i].y3;
  61                 lastX *= trans;
  62                 lastX -= shift;
  63                 cairo_move_to(ct, lastX[NR::X], lastX[NR::Y]);
  64                 break;
  65
  66             case NR_LINETO:
  67                 lastX[NR::X] = bpath[i].x3;
  68                 lastX[NR::Y] = bpath[i].y3;
  69                 lastX *= trans;
  70                 lastX -= shift;
  71                 cairo_line_to(ct, lastX[NR::X], lastX[NR::Y]);
  72                 break;
  73
  74             case NR_CURVETO: {
  75                 NR::Point  tm1, tm2, tm3;
  76                 tm1[0]=bpath[i].x1;
  77                 tm1[1]=bpath[i].y1;
  78                 tm2[0]=bpath[i].x2;
  79                 tm2[1]=bpath[i].y2;
  80                 tm3[0]=bpath[i].x3;
  81                 tm3[1]=bpath[i].y3;
  82                 tm1 *= trans;
  83                 tm2 *= trans;
  84                 tm3 *= trans;
  85                 tm1 -= shift;
  86                 tm2 -= shift;
  87                 tm3 -= shift;
  88                 cairo_curve_to (ct, tm1[NR::X], tm1[NR::Y], tm2[NR::X], tm2[NR::Y], tm3[NR::X], tm3[NR::Y]);
  89                 break;
  90             }
  91
  92             default:
  93                 break;
  94         }
  95     }
  96 }
  97
  98
  99 /*
 100   Local Variables:
 101   mode:c++
 102   c-file-style:"stroustrup"
 103   c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
 104   indent-tabs-mode:nil
 105   fill-column:99
 106   End:
 107 */
 108 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :